Biological sciences / 7. Zoology

Cand. Biol. Sci. N.N.Karpun, Cand. Agr. Sci. E.N. Zhuravleva,

Cand. Agr. Sci. Ye.A. Ignatova

The State Research Institution All–Russian Scientific and Research Institute of Floriculture and Subtropical Crops of the Russian Academy of Agricultural Sciences, Sochi, Russia, e-mail: nkolem@mail.ru

First report about invasion of Rhynchophorus ferrugineus Oliv. on Russian Black Sea coast

Abstract. The red palm weevil, Rhynchophorus ferrugineus Oliv. (Coleoptera: Curculionidae), was recorded on the Black Sea coast of Russia (Sochi) for the first time in September, 2014. This is a dangerous phytophage of palm trees which gets in trunks, feeds on core, destroys it and destroys a growing-point of a palm tree. The damages are imperceptible until the palm tree is not lost. In September, 2014, imago of red palm weevil, a larva and a pupa in cocoons were found in Phoenix canariensis and Trachycarpus fortunei, that had been delivered from Italy and landed in one of Sochi parks.

Key words: Rhynchophorus ferrugineus, Phoenix canariensis, invasion, phytophage, Black Sea coast of Russia.

Invasion of new alien species of phytophage insects may have a significant impact on the indigenous, recreational and urban plant communities. Today, phytophagous invaders represent a real threat to biodiversity and ecosystem productivity on Russian Black Sea coast. New alien species of invertebrate phytophages invade all the time, regardless of their quarantine status, becoming expansive and making this problem a global one [2, 7].

Palm trees on the Black Sea coast are “visiting card” of the resort. Currently, representatives of 9 following genera of Arecaceae family are cultivated in the territory of the Black Sea coast (Krasnodar region): Butia, Washingtonia, Livinstona, Sabal, Trachycarpus, Phoenix, Chamaerops, Erythea and Jubaea [4]. Thus, more than 1,000 different species of palm trees grow at least in the city park “Riviera”. During preparation for the XXII Olympic Winter Games in Sochi, more than 1,300 trees were planted as compensatory plantings.

As a rule, the discovery of new species occurs during phytosanitary monitoring, as it earlier occurred in the region [3, 5, 6]. There was not any information about finding Rhynchophorus ferrugineus Oliv. in Sochi until now.

In September 2014, a few Рhoenix canariensis trees died in one of local Sochi parks. The entomological expertise has established that the plants death was caused by a dangerous pest of palm trees, i.e. red palm weevil Rhynchophorus ferrugineus Oliv. (Coleoptera: Curculionidae) [1, 8, 12].

The original habitat of the red palm weevil are tropical regions of South-East Asia. The pest feeds on almost all species of palm trees, preferring Рhoenix and other large-trunked species; it harms the plantations of sugar cane and bananas. In the 1980s, the given phytophage became anthropogenically spread in the Middle East and North Africa. In 2005, R. ferrugineus was delivered to Spain, Italy, French Corsica and Cyprus; it was also registered in Israel, and has appeared in Mexico, USA and Japan since 2010 [10, 11, 13, 15]. The European Union has adopted a restriction on the importation of palms because of the invasion of this phytophage introduced with plant material. The EU countries have been struggling against the red palm weevil till the present time. However, damage to ornamental plantings is invaluable [2, 9].

The discovered phytophage was present in different phases, making it possible to give a substantive description and clarify its life cycle, using the method of growing it till imago.

The beetle of red palm weevil reaches a length from 35 to 50 mm. Imago body is oblong, slightly flattened on top; elytra are hard; the color is from pale ocher to rusty brown with dark spots on the back. Sexual dimorphism is ill-defined: females are slightly larger than males with a longer rostrum and more convex elytra, while males have a longitudinal “mane” of red hairs on the upper side of the rostrum. Paws are connected with the body like “a screw and a screw nut” which helps beetles move freely inside the wood.

The larva reaches 5 cm, it is legless, C-shaped, covered with sparse hairs, has whitish-cream color with a chitinized brown head consisting of a head thorax with powerful chewing mandibles.

Brown cocoons are made of palm fiber, up to 5 cm. They are, as a rule, in palm petioles, located close to the trunk. The pupae are shaped like beetles with mild rudiments of wings, paws, and rostrum.

The red palm weevil refers to monovoltine species, has one generation, coinciding with the annual cycle, but diapausing individuals can increase its duration. In the humid subtropical Black Sea coast of Russia, the development of the eggs can take up to 7 days, the larvae – up to 4 months, pupae – for about 3 weeks. The female lays on average 150 or 180 eggs on the top of the palms close to the growing point as much as possible [9, 14, 15]. Hatched larvae penetrate the stem and feed on the core, destroying it and killing the growing point of palm trees. The damage is almost unnoticeable as long as the palm tree does not die.

The key elements, which can determine the damage made by the red palm weevil include desiccation of central female connector in the palm and dropping of leaves, as a result the crown acquires a triangular form, and later – the trunks start to break and the palms die. Availability of flight holes in palm trunks up to 3 cm in diameter, as well as larvae, cocoons and pest beetles inside the trunks are a clear evidence of the pest’s presence [12].

It should be noted that the given species has a high adaptability to unfavorable factors, which is due to the evolutionary-genetic factors, since Phanerognatha Dryphthorinae had emerged in the early Mesozoic and were then developed as interstitial specialized phytophages, closely related to the plants in the phase of larvae and imago.

Invasion of the pest is entirely anthropogenic - as a result of planting material transplantotion. R. ferrugineus with its special morphological and biological characteristics has a weak flying ability, and is able to settle in a radius not exceeding 5 km [1, 16]. We should also mention the fact that the species is characterized by a long-term diapause in imago phase within the biotope changes, occurring due to the anthropogenic invasion [1, 13, 14]. The phenomena of thanatosis and catalepsy (imitation of death, long-term standstill, with the lack of reaction to any type of stimulation and changes in metabolism), which are inherent in the red palm weevil R. ferrugineus and are the factors to adapt to the changing life conditions suggest that it is a dangerous and highly aggressive species [12, 16].

A detailed survey of plants planted in the city for the last two years, has revealed the red palm weevil not only in Phoenix canariensis hort. ex Chabaud, but also in Trachycarpus fortunei H. Wendl. All the infected plants have been brought from Italian nurseries. In other palm species growing in Sochi, this type has not been registered yet. However, despite the fact that Rhynchophorus ferrugineus is characterized as an oligophage of palm family (Arecaeae), the feeding was recorded in the representatives of Agavaceae (Agave americana) and Poaceae (Saccharum officinarum), as well as in such types of palm trees as Calamus merrillii, Caryota cumingii, Cocos nucifera, Elaeis guineensis, Metroxylon sagu, Oneosperma tigillarium, Sabal umbraculifera and Trachycarpus fortunei [12]. This fact greatly expands the range of trophic preferences in the phytophage together with a low competition volume, thereby significantly increasing the aggressiveness from Rhynchophorus ferrugineus.

It is obvious that this species has been delivered to Russian Black Sea coast together with the planting material. Taking into account the number of palms, introduced in the period from 2012 till 2014, and the pest’s secretive way of life, we can predict the outbreak of the invasive pest in the next two years. Nowadays, palm trees growing in arboretums and urban spaces have been thoroughly examined; recommendations for integrated plant protection have been presented; preventive measures have been carried out. Observations on the palm trees, as well as monitoring and entomological control on the Black Sea coast with the object to find out the invader’s settlement will continue.

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